1+ import { Connection , PublicKey , clusterApiUrl , Cluster , Commitment , AccountInfo , Account } from '@solana/web3.js'
2+ import {
3+ Base , Magic ,
4+ parseMappingData ,
5+ parseBaseData ,
6+ parsePriceData ,
7+ parseProductData , Price , PriceData , Product , ProductData ,
8+ Version , AccountType ,
9+ } from './index'
10+
11+ const ONES = '11111111111111111111111111111111'
12+
13+ /**
14+ * Type of callback invoked whenever a pyth price account changes. The callback additionally
15+ * gets access product, which contains the metadata for this price account (e.g., that the symbol is "BTC/USD")
16+ */
17+ export type PythPriceCallback = ( product : Product , price : PriceData ) => void
18+
19+ /**
20+ * Reads Pyth price data from a solana web3 connection. This class uses a callback-driven model,
21+ * similar to the solana web3 methods for tracking updates to accounts.
22+ */
23+ export class PythConnection {
24+ connection : Connection
25+ pythProgramKey : PublicKey
26+ commitment : Commitment
27+
28+ productAccountKeyToProduct : Record < string , Product > = { }
29+ priceAccountKeyToProductAccountKey : Record < string , string > = { }
30+
31+ callbacks : PythPriceCallback [ ] = [ ]
32+
33+ private handleProductAccount ( key : PublicKey , account : AccountInfo < Buffer > ) {
34+ const { priceAccountKey, type, product} = parseProductData ( account . data )
35+ this . productAccountKeyToProduct [ key . toString ( ) ] = product
36+ if ( priceAccountKey . toString ( ) !== ONES ) {
37+ this . priceAccountKeyToProductAccountKey [ priceAccountKey . toString ( ) ] = key . toString ( )
38+ }
39+ }
40+
41+ private handlePriceAccount ( key : PublicKey , account : AccountInfo < Buffer > ) {
42+ const product = this . productAccountKeyToProduct [ this . priceAccountKeyToProductAccountKey [ key . toString ( ) ] ]
43+ if ( product === undefined ) {
44+ // This shouldn't happen since we're subscribed to all of the program's accounts,
45+ // but let's be good defensive programmers.
46+ throw new Error ( 'Got a price update for an unknown product. This is a bug in the library, please report it to the developers.' )
47+ }
48+
49+ const priceData = parsePriceData ( account . data )
50+ for ( let callback of this . callbacks ) {
51+ callback ( product , priceData )
52+ }
53+ }
54+
55+ private handleAccount ( key : PublicKey , account : AccountInfo < Buffer > , productOnly : boolean ) {
56+ const base = parseBaseData ( account . data )
57+ // The pyth program owns accounts that don't contain pyth data, which we can safely ignore.
58+ if ( base ) {
59+ switch ( AccountType [ base . type ] ) {
60+ case 'Mapping' :
61+ // We can skip these because we're going to get every account owned by this program anyway.
62+ break ;
63+ case 'Product' :
64+ this . handleProductAccount ( key , account )
65+ break ;
66+ case 'Price' :
67+ if ( ! productOnly ) {
68+ this . handlePriceAccount ( key , account )
69+ }
70+ break ;
71+ case 'Test' :
72+ break ;
73+ default :
74+ throw new Error ( `Unknown account type: ${ base . type } )
75+ }
76+ }
77+ }
78+
79+ /** Create a PythConnection that reads its data from an underlying solana web3 connection.
80+ * pythProgramKey is the public key of the Pyth program running on the chosen solana cluster.
81+ */
82+ constructor ( connection : Connection , pythProgramKey : PublicKey , commitment : Commitment = 'finalized' ) {
83+ this . connection = connection
84+ this . pythProgramKey = pythProgramKey
85+ this . commitment = commitment
86+ }
87+
88+ /** Start receiving price updates. Once this method is called, any registered callbacks will be invoked
89+ * each time a Pyth price account is updated.
90+ */
91+ public async start ( ) {
92+ const accounts = await this . connection . getProgramAccounts ( this . pythProgramKey , this . commitment )
93+ for ( let account of accounts ) {
94+ this . handleAccount ( account . pubkey , account . account , true )
95+ }
96+
97+ this . connection . onProgramAccountChange (
98+ this . pythProgramKey ,
99+ ( keyedAccountInfo , context ) => {
100+ this . handleAccount ( keyedAccountInfo . accountId , keyedAccountInfo . accountInfo , false )
101+ } ,
102+ this . commitment ,
103+ )
104+ }
105+
106+ /** Register callback to receive price updates. */
107+ public onPriceChange ( callback : PythPriceCallback ) {
108+ this . callbacks . push ( callback )
109+ }
110+
111+ /** Stop receiving price updates. Note that this also currently deletes all registered callbacks. */
112+ public async stop ( ) {
113+ // There's no way to actually turn off the solana web3 subscription x_x, but there should be.
114+ // Leave this method in so we don't have to update our API when solana fixes theirs.
115+ // In the interim, delete callbacks.
116+ this . callbacks = [ ]
117+ }
118+ }
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